JPH0528453A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the magnetic recording medium having high output and high resolving power by specifying the film thickness of a nonmagnetic intermediate layer and the film thickness of a perpendicular magnetic recording layer to prescribed ranges. CONSTITUTION:This recording medium is constituted by successively laminating the nonmagnetic intermediate layer 3 and the perpendicular magnetic recording layer 4 via a high permeability magnetic layer 2 on a nonmagnetic substrate 1. The film thickness of this nonmagnetic intermediate layer 3 is specified to 10 to 200Angstrom and the film thickness of the perpendicular magnetic recording layer 4 to 0.05 to 0.15mum. The extremely thin nonmagnetic intermediate film 3 and the perpendicular magnetic recording film 4 which is not degraded in coercive force (Hcrt. angle) in the initial layer and has the prescribed film thickness are constituted on the nonmagnetic substrate 1 in such a manner, by which the high-density characteristics of the high output and high dissolving power are obtd. The size of the magnetic disk device is, therefore, reduced and the larger capacity thereof is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium mounted on a magnetic disk device or a magnetic tape device used as an external storage medium of a computer, and more particularly to a structure of a perpendicular magnetic recording medium excellent in storage and reproduction characteristics. Regarding Horizontal magnetic recording is a method of forming remanence in the film surface direction of a magnetic medium. In recent years, with the miniaturization or higher density of magnetic disk devices or magnetic tape devices, higher density than conventional horizontal magnetic recording has been achieved. As a recording method, a perpendicular magnetic recording method in which a residual magnetism is formed in the thickness direction of a medium film to perform signal recording is drawing attention, and research and development are being promoted by each company.

[0002]

2. Description of the Related Art Conventionally, as a medium for realizing this perpendicular magnetic recording system, a perpendicular magnetic recording layer of cobalt-chromium alloy (CoCr) or the like is formed on a non-magnetic substrate via a high dielectric constant layer of permalloy or the like. A perpendicular magnetic recording medium having a double-layer film structure (FIG. 8) is known. In FIG. 8, 11 is a non-magnetic substrate, 12 is a high magnetic permeability layer, and 14 is a perpendicular recording layer.

However, in the conventional perpendicular magnetic recording medium of this kind, the high magnetic permeability layer 12 causes a problem that the perpendicular magnetic anisotropy of the perpendicular magnetic recording layer 14 is deteriorated, and therefore, for example, Japanese Patent Laid-Open No. 58-58. -14318 and JP-A-6
In JP-A-12333413, the recording layer 14 and the high magnetic permeability layer 1 are disclosed.
It has been proposed that a non-magnetic intermediate layer 13 be provided between the two to improve the vertical orientation (FIG. 9).

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that the above-mentioned JP-A-58-14318 and JP-A-61
Based on the invention described in Japanese Patent No. 233413, a medium having a nonmagnetic intermediate layer and a medium having no nonmagnetic intermediate layer were prepared for comparison. Here, the medium structure is
The recording layer (CoCr) has a thickness of 0.3 μm, the high-permeability layer (NiFe) has a thickness of 2 μm, and titanium (Ti) is selected as the non-magnetic material for the intermediate layer.
It was 0Å.

By inserting a non-magnetic intermediate layer or the like, the vertical orientation was certainly improved from the initial layer of the recording layer (CoCr) and the formation of a clear columnar structure was promoted to provide uniform magnetic characteristics. FIG. 6 compares the coercive force (Hc⊥) in the film thickness direction of the recording layer (CoCr) with and without the non-magnetic intermediate layer (Ti). Here, in perpendicular recording, the coercive force (Hc⊥) is an important medium constant that strongly depends on the reproduction output. In the medium without the intermediate layer (Ti), the coercive force (Hc) is increased toward the interface of the high magnetic permeability layer (NiFe).
⊥) drops sharply, while the intermediate layer (Ti)
In the medium in which is inserted, a film having a uniform coercive force (Hc⊥) is formed from the initial formation layer.

FIG. 7 compares the recording density characteristics of both media on which recording and reproduction were performed using a single magnetic pole type head. As is clear from the figure, the reproduction output is the same regardless of the presence or absence of the intermediate layer (Ti), while the dividing ability (D ₅₀ ) is
Insertion of i) resulted in rather lower results. As a result of earnest studies by the inventors, in the method of recording / reproducing a perpendicular magnetic recording medium having a double-layered film structure using a single-pole type head, the surface layer side of the perpendicular recording film, which is close to the head main pole, mainly produces a reproduction output. It turned out to contribute. Therefore,
The effect of improving the output by improving the initial formation layer of the medium in which the non-magnetic layer is inserted is effective only within a predetermined perpendicular recording film thickness range. Further, the presence of the non-magnetic intermediate layer substantially increases the distance between the head and the medium. Therefore, in order to maintain high resolution characteristics, the non-magnetic intermediate layer should be as thin as possible. It is necessary.

In view of the above, the present invention defines the optimum film thicknesses for the perpendicular recording layer and the non-magnetic intermediate layer, thereby providing a perpendicular magnetic recording medium having excellent high density characteristics as compared with the conventional one. The purpose is to provide.

[0008]

In order to solve such a problem, according to the present invention, a nonmagnetic intermediate layer and a perpendicular magnetic recording layer are sequentially laminated on a nonmagnetic substrate with a high magnetic permeability magnetic layer interposed therebetween. In the perpendicular magnetic recording medium described above, the thickness of the non-magnetic intermediate layer is defined in the range of 10 to 200Å and the thickness of the perpendicular magnetic recording layer is defined in the range of 0.05 to 0.15 μm. A recording medium is provided.

[0009]

In the perpendicular magnetic recording medium of the present invention, a very thin non-magnetic intermediate film and a coercive force (Hc⊥) in the initial layer are not lowered through a high-permeability film on a non-magnetic substrate, and a predetermined film thickness is obtained. And a vertical recording film having
It is possible to obtain high-density characteristics with high output and high resolution.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples. FIG. 1 shows a perpendicular magnetic recording medium having a double film structure according to an embodiment of the present invention. 1 on a non-magnetic substrate 1 such as a glass substrate
A non-magnetic intermediate layer 3 made of titanium (Ti) having a thickness of 200Å through a permalloy high magnetic permeability layer (μ to 2000) 2 having a thickness of μm, a cobalt-chromium alloy (CoC).
The recording layer consisting of r) is sequentially laminated in the thickness range of 0.05 to 0.15 μm. In this case, the sputtering method was used for forming each layer of the medium. Of course, another thin film forming method such as a vapor deposition method may be used.

Experimental examples which form the basis of the present invention will be described below. Experimental Example 1 FIG. 2 shows the relationship between the solitary wave output ratio of the medium and the thickness of the recording layer (CoCr) depending on the presence or absence of the non-magnetic intermediate layer (Ti). At this time, a 1 μm thick permalloy film (μ to 2000) as the high magnetic permeability layer and 200 as the non-magnetic intermediate layer.
A Å thick Ti film was used, and a single pole head was used for recording and reproduction. From FIG. 2, the recording layer (CoCr) has a film thickness of 0.15.
It is clear that the insertion of the Ti layer has no effect in the thick region of μm or more.

FIG. 3 shows the relationship between the solitary wave output of a medium having a non-magnetic intermediate layer (Ti) and the film thickness of the recording layer (CoCr). The reproduction output sharply drops below 0.05 μm and gradually increases above 0.15 μm.
Since it is desirable to make the recording layer (CoCr) as thin as possible in order to obtain the above results and high resolution, the film thickness of the recording layer (CoCr) layer suitable for high density is 0.05 μm to
The range can be limited to 0.15 μm.

Experimental Example 2 FIG. 4 shows the relationship between the solitary wave output and the film thickness of the nonmagnetic intermediate layer (Ti). In this case, the high magnetic permeability layer is a 1 μm thick permalloy film (μ to 2000) and the recording layer is a 0.1 μm thick CoC film.
r film. From FIG. 4, it is clear that even if the thickness of the non-magnetic intermediate layer (Ti) is only 10 Å, it can contribute to the output improvement.

Further, FIG. 5 shows the relationship between the resolution (D ₅₀ ) and the film thickness of the nonmagnetic intermediate layer (Ti). The vertical axis is standardized by the Ti thickness of 0 μm, that is, D ₅₀ of the medium such as the Ti layer. As the thickness of the non-magnetic intermediate layer (Ti) increases, the effective spacing increases and the resolution decreases. That is, when the thickness of the non-magnetic intermediate layer (Ti) is 200 Å or more, the division ability is reduced by 20% or more.

Therefore, the film thickness of the non-magnetic intermediate layer (Ti) suitable for increasing the density can be limited to 10 to 200Å. As described above based on the experimental results, the medium structure suitable for increasing the density of the perpendicular magnetic recording medium has a nonmagnetic layer thickness of 10 to 10
Range of 200Å, thickness of perpendicular magnetic recording layer is 0.05μm
It is obvious that the range is 0.15 μm.

Although titanium (Ti) having a hexagonal close-packed lattice structure is used as the non-magnetic intermediate layer in this embodiment, other metals such as tungsten (W) and magnesium (Mg), and silicon oxide (SiO 2). ₂ ), an amorphous material such as titanium oxide (TiO ₂ ) can achieve the same effect.

[0017]

As described above, according to the present invention, a perpendicular magnetic recording medium having high output and high resolution characteristics can be realized, which contributes to miniaturization and large capacity of a magnetic disk device. Very big.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a cross-sectional structure of a perpendicular magnetic recording medium of the present invention.

FIG. 2 is a diagram showing an effect of improving output when a non-magnetic intermediate layer (Ti) is inserted.

FIG. 3 is a diagram showing the relationship between the thickness of the recording layer (CoCr) of the medium and the solitary wave output when a nonmagnetic intermediate layer (Ti) is inserted.

FIG. 4 is a diagram showing a relationship between a solitary wave output and a film thickness of a nonmagnetic intermediate layer (Ti).

FIG. 5 is a diagram showing the relationship between the dividing power and the film thickness of a non-magnetic intermediate layer (Ti).

FIG. 6 is a diagram showing a coercive force distribution in a film thickness direction of a recording layer (CoCr) layer.

FIG. 7 is a diagram showing a comparison of recording density characteristics with and without a non-magnetic intermediate layer (Ti).

FIG. 8 is a schematic diagram (Conventional example 1) showing a cross-sectional structure of a conventional perpendicular magnetic recording medium.

FIG. 9 is a schematic diagram (prior art example 2) showing a cross-sectional structure of a perpendicular magnetic recording medium having a non-magnetic intermediate layer inserted therein.

[Explanation of symbols]

1 ... Glass substrate 2 ... NiFe high magnetic permeability layer (1 μm) 3 ... Ti non-magnetic intermediate layer (10 to 200Å) 4 ... CoCr perpendicular recording layer (0.05 to 0.15 μm)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor K. Tsuyoshi             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (4)

[Claims] 1. A perpendicular magnetic recording medium in which a non-magnetic intermediate layer (3) and a perpendicular magnetic recording layer (4) are sequentially laminated on a non-magnetic substrate (1) with a high-permeability magnetic layer (2) interposed therebetween. The thickness of the non-magnetic intermediate layer (3) is in the range of 10 to 200Å, and the thickness of the perpendicular magnetic recording layer (4) is 0.05 to 0.15 μ.
A perpendicular magnetic recording medium characterized by being defined in the range of m. 2. The metal thin film having a hexagonal close-packed lattice structure is used as the non-magnetic intermediate layer (3).
The perpendicular magnetic recording medium according to 1. 3. The perpendicular magnetic recording medium according to claim 1, wherein an amorphous thin film is used as the non-magnetic intermediate layer (3). 4. The non-magnetic intermediate layer (3) is made of titanium (Ti), and the perpendicular magnetic recording layer (4) is made of cobalt-chromium alloy (CoCr). The perpendicular magnetic recording medium described.